Chapter 2. Creating Applications
2.1. Creating applications using the Developer perspective
The Developer perspective in the web console provides you the following options from the +Add view to create applications and associated services and deploy them on OpenShift Container Platform:
Getting started resources: Use these resources to help you get started with Developer Console. You can choose to hide the header using the Options menu .
- Creating applications using samples: Use existing code samples to get started with creating applications on the OpenShift Container Platform.
- Build with guided documentation: Follow the guided documentation to build applications and familiarize yourself with key concepts and terminologies.
- Explore new developer features: Explore the new features and resources within the Developer perspective.
Developer catalog: Explore the Developer Catalog to select the required applications, services, or source to image builders, and then add it to your project.
- All Services: Browse the catalog to discover services across OpenShift Container Platform.
- Database: Select the required database service and add it to your application.
- Operator Backed: Select and deploy the required Operator-managed service.
- Helm chart: Select the required Helm chart to simplify deployment of applications and services.
Event Source: Select an event source to register interest in a class of events from a particular system.Note
The Managed services option is also available if the RHOAS Operator is installed.
- Git repository: Import an existing codebase, Devfile, or Dockerfile from your Git repository using the From Git, From Devfile, or From Dockerfile options respectively, to build and deploy an application on OpenShift Container Platform.
- Container images: Use existing images from an image stream or registry to deploy it on to the OpenShift Container Platform.
- Pipelines: Use Tekton pipeline to create CI/CD pipelines for your software delivery process on the OpenShift Container Platform.
Serverless: Explore the Serverless options to create, build, and deploy stateless and serverless applications on the OpenShift Container Platform.
- Channel: Create a Knative channel to create an event forwarding and persistence layer with in-memory and reliable implementations.
- Samples: Explore the available sample applications to create, build, and deploy an application quickly.
From Local Machine: Explore the From Local Machine tile to import or upload files on your local machine for building and deploying applications easily.
- Import YAML: Upload a YAML file to create and define resources for building and deploying applications.
- Upload JAR file: Upload a JAR file to build and deploy Java applications.
Note that certain options, such as Pipelines, Event Source, and Import Virtual Machines, are displayed only when the OpenShift Pipelines Operator, OpenShift Serverless Operator, and OpenShift Virtualization Operator are installed, respectively.
To create applications using the Developer perspective ensure that:
To create serverless applications, in addition to the preceding prerequisites, ensure that:
2.1.2. Creating Sample applications
You can use the basic sample applications in the +Add flow of the Developer perspective to create, build, and deploy applications quickly.
The following procedure explains the Samples option in the Developer perspective to create a sample application.
- In the +Add view, click on the Samples tile to see the Samples page.
- On the Samples page, select one of the available sample applications to see the Create Sample Application form.
In the Create Sample Application Form:
- In the Name field, the deployment name is displayed by default. You can modify this name as required.
- In the Builder Image Version, a builder image is selected by default. You can modify this image version by using the Builder Image Version drop-down list.
- A sample Git repository URL is added by default.
- Click Create to create the sample application. The build status of the sample application is displayed on the Topology view. After the sample application is created, you can see the deployment added to the application.
2.1.3. Importing a codebase from Git to create an application
You can use the Developer perspective to create, build, and deploy an application on OpenShift Container Platform using an existing codebase in GitHub.
The following procedure walks you through the From Git option in the Developer perspective to create an application.
- In the +Add view, click From Git in the Git Repository tile to see the Import from git form.
In the Git section, enter the Git repository URL for the codebase you want to use to create an application. For example, enter the URL of this sample Node.js application
https://github.com/sclorg/nodejs-ex. The URL is then validated.
Optional: You can click Show Advanced Git Options to add details such as:
- Git Reference to point to code in a specific branch, tag, or commit to be used to build the application.
- Context Dir to specify the subdirectory for the application source code you want to use to build the application.
- Source Secret to create a Secret Name with credentials for pulling your source code from a private repository.
Optional: You can import a devfile, a Dockerfile, or a builder image through your Git repository to further customize your deployment.
- If your Git repository contains a devfile, a Dockerfile, or a builder image, it is automatically detected and populated on the respective path fields. If a devfile, a Dockerfile, and a builder image are detected in the same repository, the devfile is selected by default.
- To edit the file import type and select a different strategy, click Edit import strategy option.
- If multiple devfiles, Dockerfiles, or builder images are detected, to import a specific devfile, Dockerfile, or a builder image, specify the respective paths relative to the context directory.
After the Git URL is validated, the recommended builder image is selected and marked with a star. If the builder image is not auto-detected, select a builder image. For the
https://github.com/sclorg/nodejs-exGit URL, by default the Node.js builder image is selected.
- Optional: Use the Builder Image Version drop-down to specify a version.
- Optional: Use the Edit import strategy to select a different strategy.
In the General section:
In the Application field, enter a unique name for the application grouping, for example,
myapp. Ensure that the application name is unique in a namespace.
The Name field to identify the resources created for this application is automatically populated based on the Git repository URL if there are no existing applications. If there are existing applications, you can choose to deploy the component within an existing application, create a new application, or keep the component unassigned.Note
The resource name must be unique in a namespace. Modify the resource name if you get an error.
- In the Application field, enter a unique name for the application grouping, for example,
In the Resources section, select:
- Deployment, to create an application in plain Kubernetes style.
- Deployment Config, to create an OpenShift Container Platform style application.
- Knative Service, to create a microservice.
The Knative Service option is displayed in the Import from git form only if the Serverless Operator is installed in your cluster. For further details refer to documentation on installing OpenShift Serverless.
- In the Pipelines section, select Add Pipeline, and then click Show Pipeline Visualization to see the pipeline for the application.
- In the Advanced Options section, the Create a route to the application is selected by default so that you can access your application using a publicly available URL. You can clear the check box if you do not want to expose your application on a public route.
Optional: You can use the following advanced options to further customize your application:
Click the Routing link to:
- Customize the hostname for the route.
- Specify the path the router watches.
- Select the target port for the traffic from the drop-down list.
Secure your route by selecting the Secure Route check box. Select the required TLS termination type and set a policy for insecure traffic from the respective drop-down lists.
For serverless applications, the Knative service manages all the routing options above. However, you can customize the target port for traffic, if required. If the target port is not specified, the default port of
- Health Checks
Click the Health Checks link to add Readiness, Liveness, and Startup probes to your application. All the probes have prepopulated default data; you can add the probes with the default data or customize it as required.
To customize the health probes:
- Click Add Readiness Probe, if required, modify the parameters to check if the container is ready to handle requests, and select the check mark to add the probe.
- Click Add Liveness Probe, if required, modify the parameters to check if a container is still running, and select the check mark to add the probe.
Click Add Startup Probe, if required, modify the parameters to check if the application within the container has started, and select the check mark to add the probe.
For each of the probes, you can specify the request type - HTTP GET, Container Command, or TCP Socket, from the drop-down list. The form changes as per the selected request type. You can then modify the default values for the other parameters, such as the success and failure thresholds for the probe, number of seconds before performing the first probe after the container starts, frequency of the probe, and the timeout value.
- Build Configuration and Deployment
Click the Build Configuration and Deployment links to see the respective configuration options. Some options are selected by default; you can customize them further by adding the necessary triggers and environment variables.
For serverless applications, the Deployment option is not displayed as the Knative configuration resource maintains the desired state for your deployment instead of a
Click the Scaling link to define the number of pods or instances of the application you want to deploy initially.
For serverless applications, you can:
- Set the upper and lower limit for the number of pods that can be set by the autoscaler. If the lower limit is not specified, it defaults to zero.
- Define the soft limit for the required number of concurrent requests per instance of the application at a given time. It is the recommended configuration for autoscaling. If not specified, it takes the value specified in the cluster configuration.
- Define the hard limit for the number of concurrent requests allowed per instance of the application at a given time. This is configured in the revision template. If not specified, it defaults to the value specified in the cluster configuration.
- Resource Limit
- Click the Resource Limit link to set the amount of CPU and Memory resources a container is guaranteed or allowed to use when running.
- Click the Labels link to add custom labels to your application.
- Click Create to create the application and see its build status in the Topology view.
2.1.4. Upload JAR files for easy deployment of Java applications
You can use the JAR files in the Topology view of the Developer perspective to deploy your Java applications. You can upload a JAR file using the following options:
- Navigate to the +Add view of the Developer perspective, and click Upload JAR file in the From Local Machine tile. Browse and select your JAR file, or drag and drop a JAR file to deploy your application.
- Navigate to the Topology view and use the Upload JAR file option, or drag and drop a JAR file to deploy your application.
- Use the in-context menu in the Topology view, and then use the Upload JAR file option to upload your JAR file to deploy your application.
Use the following instructions to upload a JAR file in the Topology view to deploy a Java application:
- In the Topology view, right-click anywhere in the Topology view to see the Add to Project menu.
- Hover over the Add to Project menu to see the menu options, and then select the Upload JAR file option to see the Upload JAR file form . Alternatively, you can drag and drop the JAR file in the Topology view.
- In the JAR file field, browse for the required JAR file on your local machine and upload it. Alternatively, you can drag and drop the JAR file on the field. A toast alert is displayed at the top right if an incompatible file type is dragged and dropped on the Topology view. A field error is displayed if an incompatible file type is dropped on the field in the upload form.
- You can further specify optional Java commands to customize your deployed application. The Runtime Icon and Builder Image is selected by default. If a Builder Image is not auto-detected, select a Builder Image. If required, you can change the version using the Builder Image Version drop-down list.
- In the optional Application Name field, enter a unique name for your application for the resource labelling.
- In the Name field, enter a unique component name to name the associated resources.
- In the Resources field, choose the resource type for your application.
- In the Advanced options, click on Create a Route to the Application to configure a public URL for your deployed application.
Click Create to deploy the application. The user sees a toast notification notifying that the JAR file is being uploaded and takes a while. The toast notification also includes a link to view the build logs.Note
If the user attempts to close the browser tab while the build is running, a web alert would be displayed asking the user if they actually want to leave the page.
After the JAR file is uploaded and the application is deployed, you can see the deployment in the Topology view.
2.1.5. Using the Developer Catalog to add services or components to your application
You use the Developer Catalog to deploy applications and services based on Operator backed services such as Databases, Builder Images, and Helm Charts. The Developer Catalog contains a collection of application components, services, event sources, or source-to-image builders that you can add to your project. Cluster administrators can customize the content made available in the catalog.
- In the Developer perspective, navigate to the +Add view and from the Developer Catalog tile, click All Services to view all the available services in the Developer Catalog.
- Under All Services, select the kind of service or the component you need to add to your project. For this example, select Databases to list all the database services and then click MariaDB to see the details for the service.
Click Instantiate Template to see an automatically populated template with details for the MariaDB service, and then click Create to create and view the MariaDB service in the Topology view.
Figure 2.1. MariaDB in Topology
2.2. Creating applications from installed Operators
Operators are a method of packaging, deploying, and managing a Kubernetes application. You can create applications on OpenShift Container Platform using Operators that have been installed by a cluster administrator.
This guide walks developers through an example of creating applications from an installed Operator using the OpenShift Container Platform web console.
- See the Operators guide for more on how Operators work and how the Operator Lifecycle Manager is integrated in OpenShift Container Platform.
2.2.1. Creating an etcd cluster using an Operator
This procedure walks through creating a new etcd cluster using the etcd Operator, managed by Operator Lifecycle Manager (OLM).
- Access to an OpenShift Container Platform 4.8 cluster.
- The etcd Operator already installed cluster-wide by an administrator.
Create a new project in the OpenShift Container Platform web console for this procedure. This example uses a project called
Navigate to the Operators → Installed Operators page. The Operators that have been installed to the cluster by the cluster administrator and are available for use are shown here as a list of cluster service versions (CSVs). CSVs are used to launch and manage the software provided by the Operator.Tip
You can get this list from the CLI using:
$ oc get csv
On the Installed Operators page, click the etcd Operator to view more details and available actions.
As shown under Provided APIs, this Operator makes available three new resource types, including one for an etcd Cluster (the
EtcdClusterresource). These objects work similar to the built-in native Kubernetes ones, such as
ReplicaSet, but contain logic specific to managing etcd.
Create a new etcd cluster:
- In the etcd Cluster API box, click Create instance.
The next screen allows you to make any modifications to the minimal starting template of an
EtcdClusterobject, such as the size of the cluster. For now, click Create to finalize. This triggers the Operator to start up the pods, services, and other components of the new etcd cluster.
Click on the example etcd cluster, then click the Resources tab to see that your project now contains a number of resources created and configured automatically by the Operator.
Verify that a Kubernetes service has been created that allows you to access the database from other pods in your project.
All users with the
editrole in a given project can create, manage, and delete application instances (an etcd cluster, in this example) managed by Operators that have already been created in the project, in a self-service manner, just like a cloud service. If you want to enable additional users with this ability, project administrators can add the role using the following command:
$ oc policy add-role-to-user edit <user> -n <target_project>
You now have an etcd cluster that will react to failures and rebalance data as pods become unhealthy or are migrated between nodes in the cluster. Most importantly, cluster administrators or developers with proper access can now easily use the database with their applications.
2.3. Creating applications using the CLI
You can create an OpenShift Container Platform application from components that include source or binary code, images, and templates by using the OpenShift Container Platform CLI.
The set of objects created by
new-app depends on the artifacts passed as input: source repositories, images, or templates.
2.3.1. Creating an application from source code
new-app command you can create applications from source code in a local or remote Git repository.
new-app command creates a build configuration, which itself creates a new application image from your source code. The
new-app command typically also creates a
Deployment object to deploy the new image, and a service to provide load-balanced access to the deployment running your image.
OpenShift Container Platform automatically detects whether the pipeline or source build strategy should be used, and in the case of source builds, detects an appropriate language builder image.
To create an application from a Git repository in a local directory:
$ oc new-app /<path to source code>
If you use a local Git repository, the repository must have a remote named
origin that points to a URL that is accessible by the OpenShift Container Platform cluster. If there is no recognized remote, running the
new-app command will create a binary build.
To create an application from a remote Git repository:
$ oc new-app https://github.com/sclorg/cakephp-ex
To create an application from a private remote Git repository:
$ oc new-app https://github.com/youruser/yourprivaterepo --source-secret=yoursecret
If you use a private remote Git repository, you can use the
--source-secret flag to specify an existing source clone secret that will get injected into your build config to access the repository.
You can use a subdirectory of your source code repository by specifying a
--context-dir flag. To create an application from a remote Git repository and a context subdirectory:
$ oc new-app https://github.com/sclorg/s2i-ruby-container.git \ --context-dir=2.0/test/puma-test-app
Also, when specifying a remote URL, you can specify a Git branch to use by appending
#<branch_name> to the end of the URL:
$ oc new-app https://github.com/openshift/ruby-hello-world.git#beta4
220.127.116.11. Build strategy detection
If a Jenkins file exists in the root or specified context directory of the source repository when creating a new application, OpenShift Container Platform generates a pipeline build strategy. Otherwise, it generates a source build strategy.
Override the build strategy by setting the
--strategy flag to either
$ oc new-app /home/user/code/myapp --strategy=docker
oc command requires that files containing build sources are available in a remote Git repository. For all source builds, you must use
git remote -v.
18.104.22.168. Language detection
If you use the source build strategy,
new-app attempts to determine the language builder to use by the presence of certain files in the root or specified context directory of the repository:
Table 2.1. Languages detected by
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After a language is detected,
new-app searches the OpenShift Container Platform server for image stream tags that have a
supports annotation matching the detected language, or an image stream that matches the name of the detected language. If a match is not found,
new-app searches the Docker Hub registry for an image that matches the detected language based on name.
You can override the image the builder uses for a particular source repository by specifying the image, either an image stream or container specification, and the repository with a
~ as a separator. Note that if this is done, build strategy detection and language detection are not carried out.
For example, to use the
myproject/my-ruby imagestream with the source in a remote repository:
$ oc new-app myproject/my-ruby~https://github.com/openshift/ruby-hello-world.git
To use the
openshift/ruby-20-centos7:latest container image stream with the source in a local repository:
$ oc new-app openshift/ruby-20-centos7:latest~/home/user/code/my-ruby-app
Language detection requires the Git client to be locally installed so that your repository can be cloned and inspected. If Git is not available, you can avoid the language detection step by specifying the builder image to use with your repository with the
-i <image> <repository> invocation requires that
new-app attempt to clone
repository to determine what type of artifact it is, so this will fail if Git is not available.
-i <image> --code <repository> invocation requires
repository to determine whether
image should be used as a builder for the source code, or deployed separately, as in the case of a database image.
2.3.2. Creating an application from an image
You can deploy an application from an existing image. Images can come from image streams in the OpenShift Container Platform server, images in a specific registry, or images in the local Docker server.
new-app command attempts to determine the type of image specified in the arguments passed to it. However, you can explicitly tell
new-app whether the image is a container image using the
--docker-image argument or an image stream using the
If you specify an image from your local Docker repository, you must ensure that the same image is available to the OpenShift Container Platform cluster nodes.
22.214.171.124. Docker Hub MySQL image
Create an application from the Docker Hub MySQL image, for example:
$ oc new-app mysql
126.96.36.199. Image in a private registry
Create an application using an image in a private registry, specify the full container image specification:
$ oc new-app myregistry:5000/example/myimage
188.8.131.52. Existing image stream and optional image stream tag
Create an application from an existing image stream and optional image stream tag:
$ oc new-app my-stream:v1
2.3.3. Creating an application from a template
You can create an application from a previously stored template or from a template file, by specifying the name of the template as an argument. For example, you can store a sample application template and use it to create an application.
Upload an application template to your current project’s template library. The following example uploads an application template from a file called
$ oc create -f examples/sample-app/application-template-stibuild.json
Then create a new application by referencing the application template. In this example, the template name is
$ oc new-app ruby-helloworld-sample
To create a new application by referencing a template file in your local file system, without first storing it in OpenShift Container Platform, use the
-f|--file argument. For example:
$ oc new-app -f examples/sample-app/application-template-stibuild.json
184.108.40.206. Template parameters
When creating an application based on a template, use the
-p|--param argument to set parameter values that are defined by the template:
$ oc new-app ruby-helloworld-sample \ -p ADMIN_USERNAME=admin -p ADMIN_PASSWORD=mypassword
You can store your parameters in a file, then use that file with
--param-file when instantiating a template. If you want to read the parameters from standard input, use
--param-file=-. The following is an example file called
Reference the parameters in the file when instantiating a template:
$ oc new-app ruby-helloworld-sample --param-file=helloworld.params
2.3.4. Modifying application creation
new-app command generates OpenShift Container Platform objects that build, deploy, and run the application that is created. Normally, these objects are created in the current project and assigned names that are derived from the input source repositories or the input images. However, with
new-app you can modify this behavior.
new-app output objects
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Other objects can be generated when instantiating templates, according to the template.
220.127.116.11. Specifying environment variables
When generating applications from a template, source, or an image, you can use the
-e|--env argument to pass environment variables to the application container at run time:
$ oc new-app openshift/postgresql-92-centos7 \ -e POSTGRESQL_USER=user \ -e POSTGRESQL_DATABASE=db \ -e POSTGRESQL_PASSWORD=password
The variables can also be read from file using the
--env-file argument. The following is an example file called
POSTGRESQL_USER=user POSTGRESQL_DATABASE=db POSTGRESQL_PASSWORD=password
Read the variables from the file:
$ oc new-app openshift/postgresql-92-centos7 --env-file=postgresql.env
Additionally, environment variables can be given on standard input by using
$ cat postgresql.env | oc new-app openshift/postgresql-92-centos7 --env-file=-
BuildConfig objects created as part of
new-app processing are not updated with environment variables passed with the
18.104.22.168. Specifying build environment variables
When generating applications from a template, source, or an image, you can use the
--build-env argument to pass environment variables to the build container at run time:
$ oc new-app openshift/ruby-23-centos7 \ --build-env HTTP_PROXY=http://myproxy.net:1337/ \ --build-env GEM_HOME=~/.gem
The variables can also be read from a file using the
--build-env-file argument. The following is an example file called
Read the variables from the file:
$ oc new-app openshift/ruby-23-centos7 --build-env-file=ruby.env
Additionally, environment variables can be given on standard input by using
$ cat ruby.env | oc new-app openshift/ruby-23-centos7 --build-env-file=-
22.214.171.124. Specifying labels
When generating applications from source, images, or templates, you can use the
-l|--label argument to add labels to the created objects. Labels make it easy to collectively select, configure, and delete objects associated with the application.
$ oc new-app https://github.com/openshift/ruby-hello-world -l name=hello-world
126.96.36.199. Viewing the output without creation
To see a dry-run of running the
new-app command, you can use the
-o|--output argument with a
json value. You can then use the output to preview the objects that are created or redirect it to a file that you can edit. After you are satisfied, you can use
oc create to create the OpenShift Container Platform objects.
new-app artifacts to a file, run the following:
$ oc new-app https://github.com/openshift/ruby-hello-world \ -o yaml > myapp.yaml
Edit the file:
$ vi myapp.yaml
Create a new application by referencing the file:
$ oc create -f myapp.yaml
188.8.131.52. Creating objects with different names
Objects created by
new-app are normally named after the source repository, or the image used to generate them. You can set the name of the objects produced by adding a
--name flag to the command:
$ oc new-app https://github.com/openshift/ruby-hello-world --name=myapp
184.108.40.206. Creating objects in a different project
new-app creates objects in the current project. However, you can create objects in a different project by using the
$ oc new-app https://github.com/openshift/ruby-hello-world -n myproject
220.127.116.11. Creating multiple objects
new-app command allows creating multiple applications specifying multiple parameters to
new-app. Labels specified in the command line apply to all objects created by the single command. Environment variables apply to all components created from source or images.
To create an application from a source repository and a Docker Hub image:
$ oc new-app https://github.com/openshift/ruby-hello-world mysql
If a source code repository and a builder image are specified as separate arguments,
new-app uses the builder image as the builder for the source code repository. If this is not the intent, specify the required builder image for the source using the
18.104.22.168. Grouping images and source in a single pod
new-app command allows deploying multiple images together in a single pod. To specify which images to group together, use the
+ separator. The
--group command line argument can also be used to specify the images that should be grouped together. To group the image built from a source repository with other images, specify its builder image in the group:
$ oc new-app ruby+mysql
To deploy an image built from source and an external image together:
$ oc new-app \ ruby~https://github.com/openshift/ruby-hello-world \ mysql \ --group=ruby+mysql
22.214.171.124. Searching for images, templates, and other inputs
To search for images, templates, and other inputs for the
oc new-app command, add the
--list flags. For example, to find all of the images or templates that include PHP:
$ oc new-app --search php